<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS_浮动后的影响</title>
    <style>
        .outer {
            width: 500px;
            background-color: gray;
            border: 1px solid black;
        }

        .box {
            width: 100px;
            height: 100px;
            background-color: skyblue;
            border: 1px solid black;
            margin: 10px;
        }

        .box1,
        .box2,
        .box3 {
            float: left;
        }
    </style>
</head>

<body>
    <div class="outer">
        <div class="box box1">1</div>
        <div class="box box2">2</div>
        <div class="box box3">3</div>
    </div>
</body>

</html>